The present invention relates to a detonator in general, and more particularly to a detonator which is protected against undesired triggering as a result of shock waves or the like.
Detonators of this type are used primarily in military applications, for example in land mines. It is known from the prior art to provide such a detonator in which a housing accommodates a firing cap and a firing pin which is urged towards the firing cap, to impact the same, by a biasing spring. A wire retaining ring of spring wire is formed to a configuration resembling three laterally adjacent rings of which the center one is approximately half as large as the two outer ones and is lodged in a conical circumferential groove formed in the exterior surface of the firing pin. The ends of the wire which is formed to this configuration are soldered together. The conical configuration of the groove tends to act like a wedge upon the center ring portion and tends to expand the same. This retaining ring, or rather retaining clip, is in flat engagement with an end of the housing and constitutes the sole means of holding the firing pin after the safety pin of the detonator has been removed. This means that once the safety pin has been removed, the only thing that keeps the firing pin from impacting the firing cap is the spring tension of the retaining clip. This is a highly dangerous construction since the resilience of the spring wire of the retaining clip deteriorates over a period of time so that the biasing action of the firing-pin biasing spring is capable of pulling the firing pin out of the center ring of the retaining clip and detonating the device. In fact, the soldering-together of the free ends of the wire to form it to the desired retaining-clip configuration and the heat which is transmitted to the wire during that operation, itself tends to counteract the springiness of the wire. Moreover, the solder joint itself tends over a period of time to become brittle and can break under the stress exerted upon it by the tendency of the two ends of the wire of the retaining clip to move apart, especially under the wedging action exerted upon them by the spring-biased firing pin. If for any of these reasons the detonator operates accidentally, this represents an exceedingly high degree of danger for human life, especially as this type of detonator is primarily used in land mines, and even more particularly in anti-personnel mines of the "bounce" type which, when detonated, are "bounced" into the air by the explosion of a small charge whereupon the major charge is triggered in order to do as much damage to personnel as possible by the mine splinters and/or shrapnel. As example of this type of mine is the "Claymore" mine.
Aside from this danger of undesired operation, the prior-art detonator has a further disadvantage, namely its susceptibility to triggering by enemy action. It is conventional practice to attempt to disrupt a mine field by bringing it under cannon fire to detonate the mines, or else by shooting special mine-clearing devices, such as rope-ladders or the like which carry explosives, into the air over the mine field so that they drop onto the mine field and detonate their explosives with the purpose of in turn detonating the mines. Under either of these circumstances the detonators of the mines in a mine field are subjected to very high pressure bursts, possibly even atomic bursts, which either lead to an immediate detonation of the prior-art detonator due to high shock wave pressures acting upon the firing pin and capable of pushing it through and out of the retaining clip, or at the very least lead to dangerous deformations or shifting of the retaining clip.
Evidently, premature detonation of the mines in a mine field by one of the aforementioned approaches is undesired since it defeats the blocking action which is the main purpose of a mine field. On the other hand, deformations of the retaining clip are undesirable because they make the detonator highly unstable and deny the defender the latter possibility of clearing the mine field by conventional mineclearing equipment, i.e., without having to explode the mines. This causes new dangers and high expenses.